This application claims the priority of Japanese Patent Application No. 2000-233592 filed Aug. 1, 2000 in Japan, the entire contents of which are herein incorporated by reference.
1. Field of Industry
The present invention pertains to a substrate processing device and processing method and, in particular, it relates to a substrate-processing device, employed in the field of semiconductors and magnetic films, in which substrates are continuously processed while being rotated in a highly purified atmosphere using a magnetic coupling-type rotation introduction mechanism.
2. Description of Related Art
In processes that involve the processing of substrates in a vacuum atmosphere, by way of example, in sputtering or the like, to increase film uniformity on the substrate surface, the film must be deposited while the substrate is being rotated. In addition, and in particular for the manufacture of film of a magnetic material in which the oxygen and carbon contained in the atmosphere must be removed as much as possible, the film must be deposited in a highly purified atmosphere.
In a substrate rotation introduction mechanism of the substrate processing device enables affords the deposition of a film of improved film-thickness uniformity in a highly purified atmosphere in this way, a can-seal type magnetic coupling-type rotation introduction mechanismxe2x80x94in which a rotating body is provided in a vacuum and another rotating body, separated from the rotating body thereof by a vacuum wall, is provided in the atmospheric side, and a magnetic coupling is effected therebetween to transmit the rotational movement from the atmospheric sidexe2x80x94is employed. Because the can-seal type magnetic coupling-type rotation introduction mechanism is one in which rotational movement of an exterior rotating body is transmitted to an interior rotating body by way of magnetic coupling, without the employment of a rotating shaft that passes through the vacuum wall separating the vacuum and atmosphere, it is suitable for employment in substrate processing in an ultra-high vacuum and a highly purified atmosphere. A description is given, based on FIG. 6, of one example of a sputtering device in which a can-seal type magnetic coupling-type rotation introduction mechanism such as this is employed.
The device of FIG. 6 is a sputtering device employed for the formation of a pin layer of a GME (Giant Magnetoresistive) structure used in magnetic heads and nonvolatile memory).
A substrate holder 5, which holds a substrate 3, and a sputtering target above this, but not shown in the diagram, is included within a vacuum chamber 1. In addition, a magnet 212, for imparting a magnetic field in a predetermined direction of the substrate during formation of the film, is attached to the circumference of the substrate holder 5, and rotation is effected with the direction of the magnetic field and the predetermined direction of the substrate in alignment. The rotation of the substrate holder 5 and the magnet 212 is controlled by a can seal-type magnetic coupling-type rotation introduction mechanism.
The can seal-type magnetic coupling-type rotation introduction mechanism is separated into a vacuum part and an atmosphere part by a vacuum container 101, and a rotating shaft 102 within the vacuum is supported by the vacuum container 101 by way of bearings 103, 104. A magnetic coupler 105 and an encoder magnetic ring 106, for detection of the rotated position, are attached to the rotating shaft 102. Meanwhile, a magnet 107 and yoke 108 are attached to the atmospheric side, and the atmospheric side magnet 107 and vacuum side magnetic coupler 105 are magnetically coupled whereby the rotational movement of the magnet 107 is transmitted to the rotating shaft 102. The number of rotations and rotational angle of the rotating shaft 102 can be read by an encoder magnetic detector 109 provided on the atmospheric side.
First, exhaustion to 1.3 Pa is performed using a dry pump 231 by way of a regeneration valve 238, after which the regeneration valve 238 is closed and a dry pump 236 is cold-driven to form a state in which ultra-high vacuum exhaust is possible. The vacuum chamber 1 is exhausted from atmospheric pressure using the dry pump 231 through a pull valve 237 and then, following the closure of the pull valve 237, a main valve 235 is opened and exhaustion performed to 9.3xc3x9710xe2x88x927 Pa, which constitutes an ultra-high vacuum pressure, by the dry pump 236.
Here, from an adjacent vacuum chamber not shown in the diagram, the substrate 3 is carried by a robot, through a slit valve 232 and, by the vertical motion of a lift pin 4, is mounted on the substrate holder 5.
The substrate 3 is rotated by the can-seal type magnetic coupling-type rotation introduction mechanism 2 together with the substrate holder 5. At the stage at which the substrate has reached a predetermined rate of rotation, using a material that is spread from the sputtering target not shown in the diagram, a film is deposited on the substrate. In this way, using the rotation of the substrate, a substrate with improved film uniformity is deposited on the substrate surface. The operation is performed continuously and film is formed on a plurality of substrates.
However, a serious problem arises during the employment of a device such as that shown in FIG. 6 in that, upon the continuous manufacture of a layered structure of a magnetic head NiMn and Cu film on a plurality of substrates, after several films have been manufactured, the desired magnetic characteristics of the film are not able to be obtained. During an examination of the various manufacturing conditions to ascertain the cause thereof, it was determined that the predetermined magnetic characteristics were able to be obtained if the film was formed following the lowering of the temperature of the substrate holder to room temperature by shutting down the device for an appropriate time. This is because the temperature of the substrate gradually increases when continuous manufacture of film is performed and, when the temperature rises, an alloy is formed at the interface of the NiMn layer and Cu layer and magnetic characteristics different to the designed value of a 2-layer structure are generated.
Thereupon, in order to investigate temperature history during continuous processing, a thermoelement was attached to the substrate and the substrate holder and the temperature shifts of the substrate holder and substrate, when 4 substrates were continuously processed, was measured. The results thereof are shown by the straight line and broken line, respectively, of FIG. 7. Here, the horizontal axis represents the processing time and the vertical axis represents the temperature. It will be noted that the tests were performed with the substrate holder stationary. As is shown by FIG. 7, it is clear that, during processing from the 1st substrate to the 4th substrate, the temperature of the substrate holder gradually increased. In addition, although the temperature of the substrate was 20(C directly after being carried by the robot, it can be seen that changes occurred in the wake of changes in temperature of the substrate holder, and that the temperature during deposition of the 4th film, by comparison with the first, had risen.
It can be seen that, for this reason, there is a drawback in the continuous processing of a plurality of substrates using the device of the prior art in that sufficient time, which involves leaving and cooling the substrate holder to room temperature, must be taken for the processing of each substrate, wherein productivity is significantly lowered.
Another substrate rotating mechanism method that has been employed hitherto is shown in FIG. 8. In this method, a direct-rotation drive shaft 401 passes through to the vacuum side from the atmospheric side, and vacuum sealing is performed using a magnetic fluid seal 402. Although it is possible to cool the substrate holder by the provision of a water pipe 403 in the center of the rotation drive shaft, a drawback exists with this magnetic fluid seal mechanism in that organic material contained in the magnetic fluid evaporates to contaminate the vacuum chamber, whereby oxygen and carbon may be contained in the film. There is a particular concern in layered films of NiMn and Cu of a reduction in quality due to contamination by carbon and, in film manufacture for which the exhaust of carbon-oxygen contaminates is required in a highly purified atmosphere, a rotation mechanism which comprises a shaft that passes through the vacuum and atmosphere, such as a magnetic fluid seal, cannot be adopted.
An object of the present invention is to provide a substrate processing device and substrate processing method in which, in a substrate processing device and substrate processing method in which substrate processing is performed continuously in a highly-purified atmosphere employing a can seal-type magnetic coupling-type rotation introduction mechanism, the temperature history of each substrate is made constant whereby deviations in processing between the substrates are reduced and an improved productivity is achieved.
An additional object of the present invention is to provide a substrate processing device and substrate processing method in which a magnetic film, with uniform magnetic characteristics, can be continually produced.
One embodiment of a substrate processing device of the present invention has an interior rotating body for a substrate holder, provided in the interior of a vacuum chamber, and an external rotating body, provided in the exterior of said vacuum chamber, which are magnetically coupled, and which comprises a can-seal type magnetic coupling-type rotation introduction mechanism which, by the rotational movement of the abovementioned exterior rotating body, controls the rotational movement of the abovementioned interior rotating body. A heat-accumulating member, maintained at a predetermined temperature, and a means for performing heat exchange between the heat-accumulating member and the abovementioned substrate holder, are provided in the vacuum chamber interior, and the substrate temperature adopted prior to substrate processing is the desired temperature
Adopting a configuration such as this, even in a highly purified atmosphere in which a can seal-type magnetic coupling-type rotation introduction mechanism is employed, it is possible to maintain the initial temperature of the substrate at a constant because of heat exchange between the heat-accumulating member and the substrate holder. And, it is possible to suppress the reduction in processing performance accompanying a rise in the temperature of the substrate holder during continuous processing, and to perform continuous and stable substrate processing.
Here, heat exchange can, by way of example, be performed by the bringing into contact of the abovementioned substrate holder and the abovementioned heat-accumulating member. Furthermore, by the introduction of a gas into the gaps between the abovementioned substrate holder and the abovementioned heat-accumulating member, the heat exchange rate can be increased even further because of the additional heat exchange through the gas.
In addition, a substrate processing device of the present invention may further include a vacuum seal member between the abovementioned substrate holder and the abovementioned heat-accumulating member and, furthermore, in that a mechanism may be provided for the filling and exhausting of a gas of pressure 13.3 Pa, or above, in a region surrounded by the abovementioned substrate holder, the abovementioned heat-accumulating member and abovementioned vacuum seal member. And, the abovementioned heat exchange is performed by way of the gas.
In this way, a space may be formed between the substrate holder and the heat-accumulating member by the seal member and, by the filling of this space with a gas of comparatively high pressure of 13.3 Pa or above, heat exchange can be efficiently performed through the gas.
Furthermore, by the optional provision of fins of a fitting structure, which do not contact each other, in respectively opposing sections of the abovementioned substrate holder and the abovementioned heat-accumulating member, the heat exchange efficiency through the gas can be improved even further.
In the substrate processing device of the present invention, it is preferable that one of the opposing surfaces of the abovementioned substrate holder and the abovementioned heat-accumulating member be electrically insulated, and that an electrostatic attraction plate be provided in the other. Small undulations may exist even if the surface of the substrate holder and heat-accumulating members are finished to a mirror surface, and there are only a few areas in which there is actual contact between the two. Thereupon, the surface area having essential contact is increased by electrostatic attraction and the heat exchange rate is improved.
Another embodiment of the present invention includes a substrate processing device in which an interior rotating body for a substrate holder, provided in the interior of a vacuum chamber, and an external rotating body, provided in the exterior of said vacuum chamber, are magnetically coupled with a can-seal type magnetic coupling-type rotation introduction mechanism which, by the rotational movement of the abovementioned exterior rotating body, controls the rotational movement of the abovementioned interior rotating body. A heat-accumulating member, maintained at a predetermined temperature, and a means for performing heat exchange between said heat-accumulating member and the abovementioned substrate holder, are provided in the vacuum chamber interior, and fins of a fitting structure, which do not contact each other, are provided in respectively opposing sections of the abovementioned substrate holder and abovementioned heat-accumulating member. When the abovementioned rotating body is rotated, gas may introduced into the gaps between said fins, and the abovementioned gas is exhausted from the under part of a bearing of the abovementioned magnetic coupled-type rotation introduction mechanism.
By the adoption of a configuration such as this, it is possible for gas flow to occur even during rotation of the substrate holder and a higher precision control of the substrate temperature is possible and, because the impurity gases emitted from the bearing part are exhausted to the exterior, substrate processing in an even higher purified atmosphere is possible.
A substrate processing method of the present invention employs a substrate processing device in which an interior rotating body for a substrate holder, provided in the interior of a vacuum chamber, and an external rotating body, provided in the exterior of said vacuum chamber, are magnetically coupled with a can-seal type magnetic coupling-type rotation introduction mechanism which, by the rotational movement of the abovementioned exterior rotating body, controls the rotational movement of the abovementioned interior rotating body. The processing of a plurality of substrates is repeatedly performed, using a heat-accumulating member, maintained at a predetermined temperature. And, a means for performing heat exchange between said heat-accumulating member and the abovementioned substrate holder, is deployed in said vacuum chamber interior so that the abovementioned substrate holder performs heat exchange with the abovementioned heat-accumulating member.